Floater designs accepted in FAST

Dear Sir

Greetings !!!

Can we perform analysis of structures other than Hywind Spar, Barge, Tlp or the structures that are mentioned on your website as a sample output.

Please find the attachment of a floater design for Offshore wind turbine. It consists of a Spar attached to a keel plate through a telescopic rod. It is basically a self installing design which facilitates a hydraulic cylinder for installation.

Is it possible to perform analysis of this structure in FAST. if necessary I can also neglect the hydraulics from the floater design during analysis.


Dear Utkarsh,

I don’t see your attachment, so, I can’t comment specifically. However, FAST has been developed to accomodate most any type of floating structure. New capabilities of FAST v8 permit several improvements over FAST v7, namely:

  • Ability to model hydrodynamics via potential flow (WAMIT), strip theory, or a combination of the two for large-volume, small volume, and multi-member substructures.
  • A linear state-space-based radiation formulation alternative to convolution.
  • Ability to model multi-segmented mooring systems (currently quasi-statically).

(A new release of FAST v8 is due out soon where these features will function better than in the previous release.)

Ongoing developments include:

  • Wave directional spreading
  • 2nd-order hydrodynamics (both potential flow and wave kinematics for strip theory)
  • Mooring dynamics

One of the key limitations of FAST flor floating wind turbines is the lack of ability currently to model the structural elasticity of the floating substructure.

Best regards,

Dear Sir,

Do we have to include the mass(and mass moment of inertia) properties of wind turbine while modeling the substructure in wamit or we only have to model the substructure itself, excluding the wind turbine mass properties.


A similar question has been answered in the following forum topic: http://forums.nrel.gov/t/about-wamit-model-for-5mw-oc3-hywind/482/1.

Best regards,